Total harmonic distortion plus noise vs. output level in milliwatts at 1 kHz into a 32-ohm load, for the Fiio E6 in normal mode (red trace), the Fiio E6 in high-gain mode (yellow trace), the Fireye Mini (cyan trace), and the GoVibe MBA (purple trace).
Total harmonic distortion plus noise vs. output level in milliwatts at 1 kHz into a 250-ohm load, for the Fiio E6 in normal mode (red trace), the Fiio E6 in high-gain mode (yellow trace), the Fireye Mini (cyan trace), and the GoVibe MBA (purple trace).
Most headphone amps aren’t made for the way we use headphones. Even many small models are too big to slip comfortably into a pocket. And most require power from an AC wall wart or a USB port. What use is that when you’re stuck in seat 34B of a Boeing 757, miles above Enid, Oklahoma, struggling to get better sound from your smartphone?
Fortunately, there are a few headphone amps that seem purpose-built for just such a scenario. They’re tiny — smaller, even, than a typical matchbox — and they’re powered by internal rechargeable batteries. They have 3.5-mm stereo analog inputs, so you can plug them into any audio source with an analog output. You can use them anywhere you go, with any source you happen to have. A couple of them even fit on keyrings.
But can such a small, simple amplifier really do anything to boost your sound quality, especially when it’s amplifying signals from your phone or computer’s lo-fi internal digital-to-analog converter (DAC)? As a headphone enthusiast who’s always on the go, that’s what I wanted to know.
So I rounded up three choice samples of the genre and hauled them along on my holiday travels this year. All three are compact enough to slip into a pocket. All three charge via a mini USB jack. And all three come with a short 3.5-mm–to–3.5-mm cable for connecting them to your phone or computer.
I tested each amp by feeding it signals from my Motorola Droid Pro smartphone. I used various sets of in-ear monitors, the type of headphone mostly likely to be used with ultracompact amps like these. My main IEM for testing these was the TDK BA100. I also tried other models, including the SOL Republic Amps HD and the Phonak Audéo PFE 232. However, I was unable to get the Fiio E6 headphone amp to work with the four-conductor plugs used on the latter two models (because each is equipped with an onboard mic and a push-to-talk inline control) — an important consideration if you use headphones equipped with this feature.
After listening to the amps, I then subjected them to the unforgiving judgment of my Audio Precision audio analyzer, testing distortion, output, and frequency response the same way Sound+Vision would with an amplifier or receiver.
To my immense surprise, the differences among these amps were colossal, both to my ears and the analyzer.
Are Apple devices known to have decent quality amps already? Because I just got a Fiio E6 and I'm having a really difficult time finding much difference with and without the amp on my iPhone 4, iPod Nano or MBP. I've listened to a wide range of music on all three devices mostly with a pair of $100 Sony circumaural phones (MDR-V6). I've also tried using some cheap ($20) IEMs and don't see much difference with the amp present or absent on any of these devices. For $30, I don't regret the purchase since I can use the E6 while travelling and keep the volume output on my audio devices low to conserve the battery.
Yes, Apple portable products have a good reputation for audio quality. I've measured a couple of them and of course listened to a lot of them, and the qualtiy is excellent for portable products.
Also, I found that of the three amps tested, the E6 sounded the least different from my Droid alone, as long as I didn't use any of the EQ modes. The differences are easist to hear on treble-heavy recordings, such as high-quality recordings of acoustic guitars.
@brentbutterworth I have a pair of quite good IEMs and I just purchased the Fiio E6, as well as the Fiio L3 LOD. I am planning on using this with my Ipod and Ipad when I am on the go as I travel quite a bit. Would there be a better system to get a HIFI on the go, without spending hundreds on something like the NuForce iDo?
@monney - We have some ideas for getting high-resolution output from your iOS devices, at a variety of price points, in this piece: http://www.soundandvisionmag.com/article/ipad-high-rez-digital-transport...
Those solutions involve a couple of additional external devices, so I'm not sure you can beat an LOD cable and external mini headphone amp for pure portability, but there are many options nowadays.
Please check it out and let us know if anything looks like a possibility for you.